Abstract
Objective:
To determine if human Zn absorption adapts to chronic high Zn intakes.
Methods:
Zn absorption was measured at 0, 8, and 16 wk in healthy postmenopausal women who consumed controlled diets with approximately 5 mg Zn from food, supplemented to 14 (n = 6), 32 (n = 3), or 47 (n = 3) mg Zn/d for 22 wk. Zn absorption for 1 day was determined by (65)Zn-labeling of meals and whole body scintillation counting.
Results:
At wk 0, less Zn was absorbed from diets with 14, compared with 32 or 47 mg/d (4.6, 8.7, and 10.3 mg/d, respectively; pooled SE = 0.9; p < 0.05). These differences were not apparent at wk 8 (5.4, 5.8, 6.4; NS) and became negligible by wk 16 (5.0, 5.0, 5.1; NS). Plasma Zn concentrations were unaffected. The results are consistent with a saturation response model of Zn absorption.
Conclusion:
Within several weeks, postmenopausal women biologically adapted to absorb a relatively uniform amount of 5 mg Zn/d when controlled, Zn-supplemented diets supplied consistent Zn intakes between 14 and 47 mg/d.
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